The present invention relates to devices for conveying fluid, and more particularly to devices for diffusing fluid into a body of fluid.
A stratified chilled water storage tank simultaneously stores warm water and cool water in a single body of water. The tank maintains the warm water and the cool water as two separate temperature zones. The upper portion of the tank contains a warm water zone. The lower portion of the tank contains a cool water zone. The warm water tends to stay in the upper portion because it is less dense, while the cool water tends to stay in the lower portion because it is more dense.
The separation of the warm water zone and the cool water zone is called stratification. Stratification minimizes mixing between the zones, and is an important feature in the stratified chilled water storage tank. The stratification (i.e. separation of temperate zones) tends to remain in effect so long as the body of water is not disturbed by water turbulence or an uneven flow of water.
In the stratified chilled water storage tank the warm upper zone and the cool lower zone are separated by a thermocline. The thermocline is a relatively thin layer of water. Within this layer, there is a rapid decrease in temperature with respect to depth. The thin depth of the thermocline is an important feature in the stratified chilled water storage tank. The thermocline separates the temperature zones, and tends to remain thin so long as the body of water is not disturbed by water turbulence or an uneven flow of water.
The body of water in the stratified chilled water storage tank may become subject to water turbulence or an uneven flow of water when water is transferred into or out of the tank. The tank transfers the warm water or the cool water into or out of the tank, based on needs outside the tank, such as for a plant cooling system. The tank typically transfers water in and out by using a water diffuser.
The water diffuser typically comprises a pair of opposed arrangements of multiple pipe sections, one adjacent the top of the tank and one adjacent the bottom of the tank. Each pipe section contains at least one opening through its wall. Each pipe section typically contains a plurality of these openings. The opening(s) allow water to pass between the interior of each pipe section and the body of water in the tank. The water diffuser reduces water turbulence and uneven flows in a tank by controlling the nature, direction and distribution of water flow as water is transferred into and out of the tank.
There are several common pipe arrangements for water diffusers in stratified chilled water storage tanks. In cylindrical tanks, water diffusers are commonly arranged so that the plurality of pipes form an octagon shape. The octagon arrangement is an attempt to approximate the round shape of a typical cylindrical tank. In a typical octagon-shaped design a set of four distribution pipes, which carry the water to be diffused into the tank, are equally spaced throughout the octagon-shaped diffuser so every other diffuser pipe section has a distribution pipe directly feeding it, while the remaining diffuser pipe sections do not. Therefore, in order for the water to reach those pipe sections in the plurality that are not directly connected to a distribution pipe, the fluid must travel through a forty-five degree turn. Although an octagon design closely approximates the round shape of a cylindrical tank, an octagon requires several pipe sections and pipe turns. Octagonal designs are not ideal because they create water turbulence within the diffuser pipe sections and uneven distribution into the tank.